Karyotypes, male meiosis and comparative FISH mapping of 18S ribosomal DNA and telomeric (TTAGG)n repeat in eight species of true bugs (Hemiptera, Heteroptera)

134

In this paper, we determine by fluorescent in situ hybridization the variability in the chromosomal location of 45S rDNA clusters in 38 species belonging to 7 genera of the Triatominae subfamily, using a triatomine-specific 18S rDNA probe. Our results show a striking variability at the inter- and intraspecific level, never reported so far in holocentric chromosomes, revealing the extraordinary genomic dynamics that occurred during the evolution in this group of insects. Our results also demonstrate that the chromosomal position of rDNA clusters is an important marker to disclose chromosomal differentiation in species karyotypically homogenous in their chromosome number.

Section: Genus Triatomasupporting

confidence: 78%

“…2 d) and different autosomal numbers (18 or 20 chromosomes). Papeschi and Bressa, 2006a, b;Grozeva et al, 2010Grozeva et al, , 2011. This is the first report attempting to address and study the variability of the 45S rDNA cluster location in a great number of species included in a single subfamily of Heteroptera.…”

Section: Genus Triatomamentioning

confidence: 99%

High Dynamics of rDNA Cluster Location in Kissing Bug Holocentric Chromosomes (Triatominae, Heteroptera)

Panzera

Pita

Ferreiro

et al. 2012

134

“…The (TTAGG) n motif is canonical and considered ancestral for insects and arthropods as a whole [Sahara et al, 1999;Frydrychová et al, 2004], although it has been variably lost during the evolution of some orders, such as Diptera, Coleoptera, Hymenoptera, and Hemiptera [Sahara et al, 1999;Frydrychová et al, 2004;Gokhman et al, 2014]. Among hemipterans, the apomorphic heteropterans Cimicomorpha (families Miridae, Cimicidae, and Tingidae) and Pentatomomorpha (families Pyrrhocoridae and Pentatomidae) lost the (TTAGG) n ancestral motif [Frydrychová et al, 2004;Grozeva et al, 2011;Golub et al, 2015]. However, (TTAGG) n was not lost in other groups, including 4 aphid species [Monti et al, 2011], in the coccid Planococcus li- lacinus [Mohan et al, 2011], in the suborder Coleorrhyncha , in the heteropteran infraorder Nepomorpha , and in Auchenorrhyncha representatives [Frydrychová et al, 2004;Maryańska-Nadachowska et al, 2012;Golub et al, 2014;Kuznetsova et al, 2015b].…”

Section: Discussionmentioning

confidence: 99%

Karyotypes and Repetitive DNA Evolution in Six Species of the Genus Mahanarva (Auchenorrhyncha: Cercopidae)

Anjos

Rocha

Paladini

et al. 2016

Insects of the Cercopidae family are widely distributed and comprise 59 genera and 431 species in the New World. They are xylemophagous, causing losses in agricultural and pasture grasses, and are considered as emerging pests. Chromosomally, these insects have been studied by standard techniques, revealing variable diploid numbers and primarily X0 sex chromosome systems (males). We performed chromosome studies in 6 Mahanarva (Cercopidae) species using standard and differential chromosome staining as well as mapping of repetitive DNAs. Moreover, the relationship between the repetitive DNAs was analyzed at the interspecific level. A diploid chromosome number of 2n = 19,X0 was documented, with chromosomes gradually decreasing in size. Neutral or GC-rich regions were detected which varied depending on the species. Fluorescence in situ hybridization with a (TTAGG)_n telomeric motif probe revealed terminal signals, matching those of the Cot DNAs obtained from each species, that were also restricted to the terminal regions of all chromosomes. Dot blot analysis with the Cot fraction from M. quadripunctata showed that at least part of the repetitive genome is shared among the 6 species. Our data highlight the conservation of chromosomal features and organization of repetitive DNAs in the genus Mahanarva, suggesting a low differentiation for chromosomes and repetitive DNAs in most of the 6 species studied.

“…18S rDNA and (TTAGG) n probe preparation and hybridization were carried out as described in Grozeva et al [2011] and are only briefly presented here. The 18S rDNA probe was PCR amplified and labeled with biotin using the genomic DNA of the true bug Pyrrhocoris apterus (Linneus, 1758).…”

Section: Fluorescence In Situ Hybridizationmentioning

confidence: 99%

Cytogenetic Characterization of Eight Odonata Species Originating from the Curonian Spit (the Baltic Sea, Russia) Using C-Banding and FISH with 18S rDNA and Telomeric (TTAGG)n Probes

Kuznetsova

Maryańska-Nadachowska²,

Shapoval³

et al. 2017

We studied the karyotypes of 8 dragonfly species originating from the Curonian Spit (the Baltic Sea, Russia) using C-banding and FISH with 18S rDNA and “insect” telomeric (TTAGG)_n probes. Our results show that Leucorrhinia rubicunda, Libellula depressa, L. quadrimaculata, Orthetrum cancellatum, Sympetrum danae, and S. vulgatum from the family Libellulidae, as well as Cordulia aenea and Epitheca bimaculata from the family Corduliidae share 2n = 25 (24 + X) in males, with a minute pair of m-chromosomes being present in every karyotype except for that of C. aenea. Major rDNA clusters are located on one of the large pairs of autosomes in all the species. No hybridization signals were obtained by FISH with the (TTAGG)_n probe in the examined species with the only exception of S. vulgatum. In this species, clear signals were detected at the ends of almost all chromosomes. This finding raises the possibility that in Odonata the canonical “insect” (TTAGG)_n telomeric repeat is in fact present but in very low copy number and is consequently difficult to detect by in situ hybridization. We conclude that more work needs to be done to answer questions about the organization of telomeres in this very ancient and thus phylogenetically important insect order.